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Treated Wood Waste Disposal Requirement Update

By Jennifer Lombari
Jan 01, 2021

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Treated Wood Waste (TWW)

What is Treated Wood Waste?

TWW comes from old wood that has been treated with chemical preservatives. These chemicals help protect the wood from insect attack and fungal decay while it’s being used. Fence posts, sill plates, landscape timbers, pilings, guardrails, and decking, to name a few, are all examples of chemically treated wood.

Note: The statute (HSC 25150.7) and regulations (22 CCR 67386.1 et seq.) that allow treated wood waste to be handled with alternative management standards are due to expire after December 31, 2020. After that date, all hazardous treated wood waste (not exempted by HSC 25143.1.5 as utility generated) managed in California will have to be stored and manifested as hazardous waste and transported to class I hazardous waste landfills for disposal.

**Coalition Response Letter on Questions on Handling Treated Wood Waste in California after January 1, 2021. **

The legislation that authorized the Alternative Management Standards (AMS) for treated wood waste (TWW) in Chapter 34 of the hazardous waste regulations will expire on December 31, 2020. Beginning on January 1, 2021, TWW will be a fully regulated California-only hazardous waste. DTSC has developed a fact sheet

that explains the new requirements that will apply to the management of TWW.

DTSC expects efforts in the upcoming legislative session to reinstate the AMS, or other requirements to govern the management of TWW. To facilitate the management of TWW in the interim, DTSC intends to offer interested parties a variance to allow the variance recipient’s TWW to be managed according to variance conditions that are similar to the existing AMS. The variances are intended to be short term in nature, providing time for the Legislature, DTSC, and impacted stakeholders to develop a longer-term strategy to effectively and safely manage TWW.

While DTSC intends to offer TWW variances, the forms and procedures are not yet available.  DTSC is currently developing systems and processes that will allow us to efficiently process a large number of TWW variance requests. Presently, our plan is to invite interested parties to apply for variances beginning in mid-February 2021, and to begin issuing variances on March 1, 2021.

DTSC will provide additional information and instructions about when and how to apply for a variance in the new year, including information regarding the cost of obtaining a variance. Please refer back to this webpage periodically for updates and information about applying for a variance.

It is important to note that unless and until a variance is obtained, any TWW generator, handler, transporter or disposal facility must comply with the applicable hazardous waste management requirements for the TWW they handle. Illegal management of hazardous waste can result in significant penalties for noncompliance.

DTSC will soon post responses to many of the questions it has received relating to the management of TWW. If you have additional specific questions relating to TWW management, please send them to or contact our Regulatory Assistance Officers at 800-728-6942 (800 72-TOXIC) or at

Is Treated Wood Waste Toxic?

TWW contains hazardous chemicals that pose a risk to human health and the environment. Arsenic, chromium, copper, creosote, and pentachlorophenol are among the chemicals used to preserve wood and are known to be toxic or carcinogenic. Harmful exposure to these chemicals may result from touching, inhaling or ingesting TWW particulate (e.g., sawdust and smoke).

Treated Wood Waste Report

DTSC has completed an extensive analysis of TWW pursuant to Senate Bill 162 (Galgiani, Chapter 351, Statutes of 2015).  SB 162 required DTSC to prepare a comprehensive report on rates of compliance with the Alternative Management Standards (AMS) for TWW. To meet this requirement, DTSC conducted 126 compliance inspections of TWW generators and disposal facilities in California. In addition, responses to TWW surveys from Household Hazardous Waste Collection Facilities (HHWCF), Certified Unified Program Agencies (CUPA), Solid Waste Transfer Stations and Load Check Program Facilities (SW Facility) were evaluated. DTSC’s evaluation and conclusions on rates of compliance with the AMS for TWW are discussed in this report.  To download the report, click on the link below. 

Report: California Department of Toxic Substances Control Treated Wood Waste Report, March 2019

Other Documents

Report: California Department of Toxic Substances Control Treated Wood Waste Report, June 2011

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